Ice climbers usually use ice screws to create anchor points in ice features the climbers are attempting to climb. The ice screws are typically temporarily installed in the ice as a lead climber (leader) ascends, and carabiners are often affixed to the installed ice screw. Climbing rope is generally passed through the carabiner such that if the leader falls, his or her belayer can arrest the fall by preventing the rope from running up through the carabiner from the belayer's position beneath the leader. With the climbers (leader and belayer), rope, and ice screw/carabiner so configured, force of the leader's fall is transmitted to the ice screw from the rope, and the leader is suspended from the ice screw after falling as far as slack in the rope permits. To successfully arrest the leader's fall, the ice screw must be securely installed in the ice so it does not pull out when force from the fall is transmitted to the ice screw. A following climber may remove the ice screws as he or she follows the leader's route.
The leader must usually install an ice screw with one hand because his or her other hand is occupied by grasping an ice tool (such as an ice axe), the pick of which the leader generally embeds in the ice above his or her head to help maintain a perch on the ice. The one-handed installation typically requires the leader to push against the ice screw while simultaneously rotating the screw, which initiates boring into the ice by a cutting tip of the screw.
A climber must frequently chip a small hole or depression in the ice with an ice tool, and subsequently initiate boring of the ice screw in the small hole. The initial boring of the ice screw is typically accomplished by the climber twisting his or her wrist and forearm, and is usually performed in multiple increments of rotation. Increments of rotation are typically limited to a range of about 60 degrees to about 180 degrees due to physiological constraints of human wrist/forearm rotation. When the climber first initiates boring into the ice with the ice screw, before the screw establishes sufficient purchase to remain in the ice in the absence of assistance from the climber, the climber must, between screw rotation increments, let go of the screw to unwind his or her wrist/forearm without unscrewing the ice screw. This initial boring requires considerable finesse, and must be repeated for each screw installed during a climb. Not surprisingly, the risk of dropping ice screws inadvertently while attempting to install the screws is a concern.
Where a climber is using one arm for installing an ice screw in the ice, fatigue in his or her other arm and shoulder is exacerbated because the climber is using only one arm instead of two for maintaining his or her perch on the ice. Strength available for other physically demanding aspects of ice climbing is consequently diminished. Means for reducing the time it takes to install an ice screw, and the exacerbated fatigue that accompanies such installation, is therefore needed. Reducing the risk of dropping an ice screw when first starting an installation is also highly desirable.